Variable pitch propeller



y 1941- R. TURNA I 2,241,008

VARIABLE PITCH PROPELLER Filed Jan. 24, 1939 2 Sheets-Sheet l INVENTORRu '0 w A N R U T R VARIABLE PITCH PROPELLER Filed Jan. 24, 1939 2Sheets-Sheet 2 lNVENTOR Rudo/ rna Patented May 6, 1941 2,241,008VARIABLE rrron PROPELLER couver, British Columbia,

Rudolph Turna, Van Ca nada Application January 24, 1939, Serial No.252,662

3 Claims.

This invention relates to an improved variable pitch propeller foraeroplanes.

An object of the present invention is the provision of a propellerincluding means operable from within the aeroplane for altering thepitch of the blades thereof.

Another object is the provision of means for retaining the blades of apropeller at any desired pitch as it is rotated.

Another object is the provision of very simple and yet effective meansfor altering the pitch of propeller blades.

A further object is the provision of a variable pitch propellerincluding means for preventing the pitch altering means from beingtwisted out of shape as the propeller is rotated.

It is desirable to be able to alter the pitch of the blades of apropeller when an aeroplane is taking off or landing. There arenumerousvariable pitch propellers known but these are not very practicalsince they are extremely complicated and, therefore, expensive. Theexpense, however, is not the chief drawback but the fact that thenumerous parts of these complicated devices will not stand up under thegreat strain to which they are subjected is the main reason for theirfailure.

This invention overcomes these objections by providing extremely simplemeans for varying the pitch of propeller blades. This means consists ofvery few parts and there are no gears to jam or worm gears or otherthreaded parts to strip or jam. This means for varying the pitch alsoincludes means for preventing the various working parts from twisting inrelation to each other.

due to the constant rotary motion of the propeller and particularly tosudden changes in the speed of rotation.

of the propeller illustrated in Figure 1, showing the pitch varyingmeans and an aeroplane en- .gine, with one cylinder removed for the sakeof clarity,

Figure 3 is a section taken on the line 3-3 of Figure 2, omitting thepropeller blades,

Figure 4 is a side-elevation, partly in section, of an alternative formof the invention and illustrating a two bladed propeller,

Figure 5 is a vertical section taken on the line 5-5 of Figure 4 withthe propeller blades shown in elevation,

Figure 6 is a plan view of the hub illustrated in Figure 4, the upperblade of which is shown in section,

Figure 7 is a vertical section taken on the line 1-1 of Figure 4,

Figure 8 is a side elevation, partly in section,

I of a two bladed propeller with the variable pitch means illustrated inFigures 1 and 2, and

Figure 9 is a plan view of the hub illustrated in Figure 8, the upperblade of which is shown in section.

Referring more particularly to the drawings.

. A is a variable pitch propeller adapted to be mounted on the crankshaft of an engine B of any type, the engine illustrated being of theradial type.

In Figures 1, 2 and 3 the propeller A consists of a hollow hub l0 whichis open'at its forward end, as at H, and over which a hub cap I2 isremovably held by bolts l3. The hub II] has formed therewith or securedthereto in any suitable manner a hollow extension M, which extensionextends rearwardly of the hub and is adapted to be mounted on the crankshaft (not shown) of the engine B in any desired manner,

The present invention consists essentially of a propeller mounted on thecrank shaft of an aeroplane comprising a hub, a plurality of bladespivotally mounted on the hub, a crank mounted adjacent the inner'end ofeach blade, a collar slidably mounted adjacent the hub, means connectingthe collar to the cranks, means for causing the collar to .rotate withthe hub, and means for moving the collar towards and away from the hubto turn the cranks and rotate the blades in relation the followingspecification and illustrated in the to-the hub, as more fully describedin any suitable manner.

such as by being'screwed thereon and held in place by a pin 15 extendingthrough the extension and the crank shaft.

A plurality of propeller blades are pivotally mounted on the hub In.Each propeller blade preferably consists v of a blade l6 removably'mounted on a stub shaft ll which is l'ournalled in the hub and has acrank or crank disc l8 formed on its inner end within the hub. Theblades l6 are mounted on the stub shafts II in One way of doing this isto form a socket 20 on the inner end of each blade into which the outerend of the stub shaft fits and having a bolt or pin 2| extending throughthe socket and the shaft;

A collar 22 slidably mounted on the extension I4, is provided with aplurality oftongues or keys 23 (see Fig. 7) adapted to fit into splines40 and M secured together by'bolts 42.

or grooves 24 formed in the extension. The collar 22 is provided with aperipheral groove 25 into which a yoke 26 extends. This yoke is formedwith an internally threaded boss 2? and is carried by a threadedactuating rod 23, said. rod extending back into the aeroplane (notshown) and having on its inner end a hand wheel 30. The rod is supportedin any suitable manner, such as by bearings 3| mounted on the engine B.Each propeller blade is connected to the collar 22 by a. connecting rod32, one end of which is pivotally secured to the crank disc l8 adjacentthe periphery thereof, as at 33, while the other end is pivotallyconnected to the collar by a pin 3%. Each connecting rod extends freelythrough an orifice 35 in the rear of .the hub Hi. There are four.propeller blades illustrated in Figure 1 and two in Figure 8 but it isto be understood that there may be any desired number of such blades.

Figures 4., 5 and 6 illustrate an alternative form. of the invention.These figures show a two bladed propeller but there may be as manyblades as desired. In this alternative, the hub of the propellerconsists of two identical sections Each of these sections is formed withtwo or more recesses 43, the number depending upon the number of blades,having at their inner ends enlarged portions 46. When the sections Mland H are bolted together their recesses 43 combine to make circularrecesses adapted to receive the stub shafts ll of the propeller bladeswhile the enlarged portions 44 accommodate the discs l8. In this case,the extension [4 is preferably formed with the section 40, as shown, orit may, if desired, be bolted to said section. In either case, theextension extends rearwardly through the section 4!. Cranks 41 areformed with or mounted upon the propeller blades adjacent their innerends but outside the hub. The outer ends of the connecting rods 32 arepivotally connected to the cranks 41 at 48.

When it is desired to alter the pitch of the propeller blades, the handwheel 30 is rotated in one direction or the other according to whetherthe pitch is to be increased or decreased. This turns the rod 28 whichcauses the yoke 26 and, consequently, the collar to move toward or awayfrom the hub of the propeller. This collar, owing to its connectionthrough the connecting rods 32 to the cranks mounted adjacent the innerends of the propeller blades,'causes said blades to pivot about the stubshafts I! to alter the pitch thereof.

The tongues 23 and the splines 24 ensure the collar. 22 rotating withthe propeller, thus eliminating any possibility of the connecting rodsbeing twisted out of shape owing to the rotation of the propeller or tosudden changes of speed of said rotation. Access may be gained to theinterior of the hub merely by removing the hub cap l2. Each blade lfimay be removed by withdrawing the pin or bolt 2|.

From the above, it will readily be seen that very simple and effectivemeans have been provided for varying the pitch of a propeller as itrotates, which will retain the blades'in the desired setting and whichwill not be likely to go out of working order.

Various modifications may 1 2. in this invention without departing iron:the spirit thereof or the scope of the claims, and therefore the exactforms shown are to be taken as illustrative only and not in a limitingsense, and it is desired that only such limitations shall be placedthereon as are disclosed in the prior art or are set forth in theaccompanying claims.

What I claim as my invention is:

1. A variable pitch propeller adapted to be mounted on the crank shaftof an aeroplane engine, comprising a hub, a plurality of bladespivotally mounted on the hub, a crank disc mounted at the inner end ofeach blade, a pin eccentrically mounted on the outer face of each disc,an extension extending rearwardly from the hub, said extension beingsplined, a collar slidably mounted on the extension having ton esfitting into the splines, a connecting rod pivotally connected to eachcrank disc pin at one end and to the collar at the other end, and meansfor moving the collar toward and away y from the hub to turn the cranksand the blades pivotally connected to each crank disc pin at one end andto the collar at the other end, said rods extending freely throughorifices in the rearward wall of the hub, and means for moving thecollar toward and away from the hub to turn the cranks and the blades inrelation to the hub.

3. A variable pitch propeller adapted to be mounted on the crank shaftof an aeroplane engine, comprising a hub, a plurality of stub shaftsjournalled in the hub, a blade'removably mounted on each shaft, a crankdisc mounted at the inner end of each shaft, a pin eccentrically mountedon the outer face of each disc, an extension extending rearwardly fromthe hub, said extension being splined, a collar slidalbly mounted on theextension having tongues fitting into the splines, a connecting rodpivotally connected to each crank disc pin at one end and to the collarat the other end, and means for moving the collar toward and away fromthe hub to flurgi the cranks and the blades in relation to the RUDOLPHTURNA.

